轮藻纲纲

它的分类地位仍有争议。有些植物学家认为可以将轮藻门和绿藻门纳入植物界中，但有些植物学家认为轮藻纲被编入绿藻门、链形植物门，或是链型植物下界，其他系统分类学家把轮藻纲分在轮藻门之下，因为轮藻纲与绿藻门仍有明显的差异。

且不论轮藻纲的真实分类，大多数植物学者都同意轮藻是最接近有胚植物（陆生植物）的一种生物。不管在生殖、光合作用、cpDNA（叶绿体的DNA）的分析，还是其他特征，都显示有胚植物是由轮藻演化而成。

下属

轮藻目(Charales)

轮藻科(Characeae)

Charophyceae is a class of charophyte green algae. AlgaeBase places it in division Charophyta. Extant (living) species are placed in a single order Charales, commonly known as "stoneworts" and "brittleworts". Fossil members of the class may be placed in separate orders, e.g. Sycidiales.

Charophyceae is basal in the Phragmoplastophyta clade which contains the embryophytes (land plants). In 2018, the first nuclear genome sequence from a species belonging to the Charophyceae was published: that of Chara braunii.

Description

The thallus is erect with regular nodes and internodes. At each node there is a whorl of branches. The whole plant is calcified and Equisetum-like. The internodes of the main axis consist of a single elongated cell, in Chara the internodes are corticated covering the main axis. In other genera these are absent. Where there is a single row of cortical cells the cortex is referred to as diplostichous, where there are two rows of cortical cells it is termed triplostichous. The intermodal cells elongate and do not divide, they become many times longer than broad.

Evolution

Below is a consensus reconstruction of green algal relationships, mainly based on molecular data.